Piston-actuated fluid discharge device

ABSTRACT

A device for storing and discharging fluid under high pressure includes a toroidal storage chamber and a coaxial spool, in which is mounted two plugs. One plug is formed with a bored gas discharge passage into which a nozzle insert providing a square orifice extends; this passage is normally sealed by a prestressed diaphragm. The second plug provides a cylinder slidably supporting a piston, and mounts a header plug containing gasgenerating means for driving the piston to puncture the diaphragm for releasing the gas charge. The spool is threaded in both plugs; and the storage chamber, plugs, and header plug, are connected by circumferential welds which completely seal the device. The fluid storage chamber is sealed from the gasgenerating means by spaced flanges and an O-ring so arranged on the piston as to avoid pinching and thus cracking the O-ring.

United States Patent Hanson et al.

PISTON-ACTUATED FLUID DISCHARGE DEVICE Inventors: David E. Hanson, 8'Oakridge Drive,

North Easton, Mass. 02334; Harry M. Landers, I56 Flaggler Drive,Marshfield, Mass. 02048 Filed: July 13, 1972 Appl. No.: 271,581

US. Cl. 137/68 Int. Cl B67b 7/24 Field of Search..., 222/5, 3; 280/150AB;

References Cited UNITED STATES PATENTS 8/1966 Vuyosevich 222/5 5/1967Sentz 222/5 [57] ABSTRACT A device for storing and discharging fluidunder high pressure includes a toroidal storage chamber and a coaxialspool, in which is mounted two plugs. One plug is formed with a boredgas discharge passage into which a nozzle insert providing a squareorifice extends; this passage is normally sealed by a prestresseddiaphragm. The second plug provides a cylinder slidably supporting apiston, and mounts a header plug containing gasgenerating means fordriving the piston to puncture the diaphragm for releasing the gascharge. The spool is threaded in both plugs; and the storage chamber,plugs, and header plug, are connected by circumferential welds whichcompletely seal the device. The fluid storage chamber is sealed from thegas-generating means by spaced flanges and an O-ring so arranged on thepiston as to avoid pinching and thus cracking the O-ring.

17 Claims, 4 Drawing Figures .3. Patent Oct. 21, 1975 SheetlofZ3,913,604

\ mini I X r I NV ww mm mm mm mm US. Patent Oct. 21, 1975 Sheet2of23,913,604

PISTON-ACTUATED FLUID DISCHARGE DEVICE BACKGROUND AND BRIEF DESCRIPTIONOF THE INVENTION Compact devices for discharging fluid stored under highpressure are employed in large quantity for such purposes as inflatingmarker bouys, life rafts, aeronautic and astronautic equipment, and thelike. Because of the requirement to store fluid (liquid, gas, or acombination) at very high pressures, many known devices of this natureare subject to fluid leakage through imperfectly sealed joints. Morereliable constructions tend to be excessively expensive to manufacture.Another common requirement of such devices is that the discharged fluidmust be pure, and must contain no foreign matter or other fluid. It istherefore necessary to provide a sealing device which will not shatterinto fragments when opened, and also to seal off the fluiddischarge pathfrom the pyrotechnic gas-generating devices which are used for operatingpistons or cutters for puncturing the sealing devices.

It is the general object of the present invention to provide an improvedfluid discharge device which is reliable in operation, seals the fluidcharge effectively against leakage, and is economical to manufacture. Itis another object to provide a fluid discharge device with an improveddischarge nozzle and seal arrangement. It is another object to provide afluid discharge device with an improved actuator arrangement whichaffords effective sealing against mixing of actuating gas with thestored fluid. It is another object to provide an improved actuatorarrangement which is unitarily constructed with the chamber body andwhich affords greater reliability of operation and improved economy ofassembly. It is another object to improve the sealing of a fluiddischarge device against loss of fluid pressure. Further objects andadvantages will appear as the following description proceeds.

DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims specifically pointing out the subject matter which we regard asour invention, it is believed that a clearer understanding may be gainedfrom the following detailed description of a preferred embodimentthereof, referring to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view in elevation of a preferred form of thefluid discharge device;

FIG. 2 is a bottom plan view prior to release of a fluid charge from thedevice;

FIG. 3 is a bottom plan view showing the device after the fluid chargehas been released; and

FIG. 4 is a sectional plan view taken along line 4-4 in FIG. 1, lookingin the direction of the arrows.

In the drawings, a piston-actuated fluid discharge device includes apair of annular chamber shells l and 12, which mate along lips 16 andare joined by a circumferential weld 14. A toroidal fluid chamber isdefined by the shells 10 and 12 and by an annular cylindrical spool 60received coaxially therein. A first plug member 76 and a second member18 are threadedly engaged with the spool at 64 and 17, respectively. Thestrength of the fluid chamber is increased by seating the shells l0 and12 under circumferential flanges 20 and 78 formed in the respectiveplugs.

The spool 60 is so dimensioned that it engages the plugs 18 and 76 andthe shells l0 and 12. This insures that the threads 17 and 64 are fullyengaged when the device is assembled, thereby achieving maximum burstingstrength.

The shell 10 is secured and sealed to the plug 18 by a circumferentialweld 21, while the shell 12 is similarly secured to the plug 76 by acircumferential weld 80. In assembling the device, the internal partsare first assembled with the plugs 18 and 76, the welds 21 and 80 areformed, the plugs 18 and 76 are threaded onto the spool 60 until thelips 16 meet firmly, and the weld 14 is made last.

The plug 76 is formed with a fluid discharge passage including acircular bore 82 and a threaded port 84 adapted for attachment to adischarge conduit. The interior 61 of the spool 60 communicates with thefluid storage chamber 15 through one or more openings 66 formed in thespool wall, and the fluid escapes through the bore 82 after the deviceis actuated. A sealing diaphragm 68 normally seals the bore 82, and issecured to the plug 76 by a circumferential weld 72.

It is necessary that the diaphragm open without shattering when it ispunctured, so that no fragments will be discharged with the pure fluidcharge. It has previously been discovered that a square nozzle formbacking up the sealing diaphragm will promote a clean puncture and avoidfragmentation, when the diaphragm is prestressed with crossed linearindentations extending along the diagonals of the squared nozzle, suchas shown at 75 in FIG. 2. According to previous practice, a squarednozzle was formed by broaching a plug such as 76; this is an expensivemachining procedure. We employ a circular bore 82, which is relativelyinexpensive to form, and provide a separate nozzle insert 70 which has asquared-off orifice portion 74 extending into the bore 82. The insert 70is formed of thin sheet metal and can be stamped or otherwise formed bylowcost high-production methods. The orifice portion 74 is not trulysquare, as will be seen in FIG. 2, but has corners which are rounded toa radius less than half the width of the squared orifice. This aids inpreventing shattering fragmentation of the diaphragm.

A piston or cutter 44, having a pointed tip 46, is slidably received ina cylinder 28, and is adapted to be driven downwardly as viewed in FIG.1 to puncture the diaphragm 68 at the intersection of the linearindentations 75. When the piston is actuated, the pressure of the fluidcharge in the chamber 15 and the spool 60 instantaneously rips thediaphragm along the indentations 75, and the quarters of the diaghragmfold against the walls of the orifice portion 74, as shown in FIG. 3, torelease the fluid charge.

The cylinder 28 is formed with a locating flange 29 which rests in astepped bore 27 formed in the plug 18, and abuts a circumferential seat31. The use of the flange 29 rather than the commonly used weld bead atthe top of the cylinder 28 provides greater reliability by virture ofthe greater mechanical strength of the flange. Also, the possibility ofweld defects adversely affecting the reliability of actuator firing iseliminated. The dropin cylinder 28 is locked in place by the weld bead23, which affords a more economical actuator construction. The weld bead23 unitizes the chamber and actuator construction, and increases thereliability of the enformed with a first circumferential flange 48 whichis of smaller diameter than the cylinder 28, and a second spaced-apartcircumferential flange 52 which has substantially the same diameter asthe cylinder and is slidably and conformably received therein. An O-ringseal 54 of rubber or other elastomeric material is received about areduced portion 50 between the flanges 48 and 52, and seals the cylinderagainst fluid flow around the piston. if a pair of flanges each of thesame diameter as the spool are used to-locate the seal 54 therebetween,there is a tendency for the seal to become pinched when assembled, andtherefore to fail when the piston is actuated. Wehave discovered thatthe provision of a reduced-diameter flange 48 for locating the seal withrespecttothe full-size flange 52 overcomes this problem.

To actuate the piston 44, a charge of gas-generating pyrotechnic mix 36of anyv suitable composition is placed within a tubular ferrulev 34received in the cylinder 28, behind the piston. A suitablepyrotechnicmixture has been developed for use in this application. Only a smallamount of gas-generating material is needed, as the volume of the mix isrequired to multiply only a few-fold to drive the piston forwardly toengage theflange 48 against the bottom 30 of the cylinder, terminatingthe piston stroke.

The ferrule 34 serves not only to locate the piston. in its normalretracted position shown in FIG. 1, but also serves as a measure for theproper quantity of pyrotechnic mix 36. A header plug 22 is received inthe bore 27 to enclose the charge 36. This plug receives electric leads38 and 40; these are interconnected by a fuse or bridge wire 42 which isimmersed in the charge 36, and serves to ignite it when an electricpotential is applied to the leads by suitable external means (not shown)of a conventional nature.iThe charge 36 of pyrotechnic mix is placedwithin the ferrule 34.prior to assembly of the ferrule and plug 22 withthe cylinder 28. lt is preferred to form the charge with a concavesurface 37 adjacent to the flange 52.

To seal the, device against leakage of the gas generated by the charge36, the leads 38 and 40 are sealed byv a glass bead received in a bore24 through the header plug 22. The header plug 22 is preferablyforrnedof an alloy having substantially the same coefficient of thermalexpansion as the glass bead 26, so that the glass-to-metal seal will notbe damaged by changing temperatures encountered before the device isused.

The header plug 22 is permanently attached to the plug 18 by. acircumferential weld 23 at the entrance to. the bore 27. This insuresagainst pressure leakage either from the fluid charged in the chamber15, or from the gas generated by the charge 36. Equally important, thismeasure. strengthens the device at what might otherwise be a weak point,and overcomes a tendency in prior devices for the piston-actuatingheaderplug to be.

blown out when the device is operated, thus releasing the fluid chargeand rendering the device ineffective.

Some additional advantages of the design are as follows. The designofthe actuator permits the pyrotech 'nic device 36, 34, etc., to beinspected during the fabricationof the fluiddischarge device The cutteror piston 44 and the cylinder 28v are captured in position when theheader plug 22 is located and welded in.place.-

This simplifies manufacture and secures the cylinder so that it cannotfly off when the actuator is fired. Thus the actuator is assembled asthe deviceis fabricated.

" sealing highly secure.

Within the broader aspects of the invention, we contemplate itsapplication to fluid discharge devices which are actuated mechanicallyrather than electrochemically, e.g., by driving thepiston directlyrather than through the medium of gas/generated by anelectricallyinitiated pyrotechnic mix.

Weclaim: v 1 A piston-actuated fluid-discharge device comprising, incombination:

means forming'a storage chamber for pressurized. fluid comprising anannular shell having central openings at opposite axial ends thereof, apair of plug members received conformably in said openingsand weldedcircumferentially to said shell, and an annular cylindrical spoolreceived coaxially within said shell and threaded at opposite endsthereof in said plug members, said spool being formed with an openingcommunicating the interior thereof with the interior of said shell; afirst one of said plug members being formed with a fluid dischargepassage of circular cross-section; a nozzle insert overlying an inletend of said discharge passage and formed with a squared orifice portionextending into said passage; diaphragm meansoverlying said nozzle insertand normally sealing said storage chamber from said discharge passage; asecond of said plug members being provided with means for puncturingsaid diaphragm means including cylinder-forming means extending axiallywithin said spool, a piston slidably received in said cylinder-formingmeans and having a tip adapted 1 for puncturing said diaphragm means,and gasgenerating meansreceivedin said cylinder-forming means at anend-of saidpiston opposite said tip for driving said piston forwardly insaid cylinderforming means for puncturing said diaphragm means; 1

said piston being formed with a first circumferential flange portionconformably and slidably received in said cylinder-forming means, andwith a second circumferential flange portion spaced apart along saidpiston from said first flange portion, said sec- -ond flange portionbeing circumferentially spaced apart from said cylinder-forming means;and sealing ring means received about said piston between said flangeportions and sealingly engaging said cylinder-forming means. I 2. Apiston-actuated fluid-discharge device comprising,"in combina'tion:

means forming a storage chamber for pressurized fluidincluding an outletplug member formed with a fluid discharge passage of circularcrosssection; a nozzle insert overlying an inlet end of said dischargepassage and 3 formed with a generally said orifice portion extendinginto said passage;

diaphragm means overlying said nozzle insert and normally sealing saidstorage chamber from said discharge passage;

means for puncturing said diaphragm means including cylinder-formingmeans, a piston slidably received in said cylinder-forming means andhaving a tip adapted for puncturing said diaphragm means, and means fordriving said piston forwardly in said cylinder-forming means forpuncturing said diaphragm means.

3. A device as recited in claim 2, in which said generally squaredorifice portion is formed with corners rounded to a radius less thanhalf the width of said orifice portion.

4. A device as recited in claim 2, said diaphragm being pre-stressed bymeans of crossed linear indentations extending substantially along eachdiagonal of said squared orifice portion.

5. A device as recited in claim 2, in which said chamber-forming meansincludes an annular shell having central openings at opposite axial endsthereof, a further plug member, said outlet plug member and said furtherplug member being received conformably in said openings and weldedcircumferentially to said shell, and an annular cylindrical spoolreceived coaxially within said shell and threaded at opposite endsthereof in said plug members; said spool being formed with an openingcommunicating the interior thereof with the interior of said shell, andreceiving said piston and cylinder-forming means therein in alignmentwith said diaphragm means.

6. A device as recited in claim 5, in which said means for driving saidpiston comprises gas-generating means received in said cylinder-formingmeans at an end of said piston opposite said tip, said further plugmember being formed with an axial bore receiving said cylinderformingmeans, and a header plug including meansfor actuating saidgas-generating means from an external location, said header plug beingreceived conformably in said axial bore in said further plug member andbeing circumferentially welded thereto.

7. A device as recited in claim 2, said piston being formed with a firstcircumferential flange portion conformably and slidably received in saidcylinder-forming means, and with a second circumferential flange portionspaced apart along with piston from said first flange portion towardsaid tip, said second flange portion being circumferentially spacedapart from said cylinder-forming means; together with sealing ring meansreceived about said piston between said flange portions and sealinglyengaging said cylinder-forming means.

8. A piston-actuated fluid-discharge device comprising, in combination:

means forming a storage chamber for pressurized fluid comprising anannular shell having central openings at opposite axial ends thereof, apair of plug members received conformably in said openings and weldedcircumferentially to said shell, and an annular cylindrical spoolreceived coaxially within said shell and threaded at opposite endsthereof in said plug members, said spool being formed with an openingcommunicating the interior thereof with the interior of said shell; afirst one of said plug members being formed with a fluid dischargepassage;

diaphragm means normally sealing said discharge passage, I v

a second of said .plug members being provided with meansfor puncturingsaid diaphragm means including cylinder-formingi means'ext'endingaxially within said spool, a piston slidably received in said cylinderforming means and having a tip adapted forpuncturing said diap hragmmeans, and gasgenerating means received in said cylinder-forming meansat an end of said pisto nropposite said tip for driving said pistonforwardly in said cylinderforming means for puncturing said diaphragmmeans. t

9. A device as recited in claim 8, said second plug member being formedwith a stepped axial bore providing a circumferential seat therein, saidcylinderforming means extending within said bore and being formed withan annular flange abutting said seat, together with a header plugreceived in said axial bore and overlying said flange to capture saidcylinderforming means in said second plug member, said header plug beingcircumferentially welded to said second plug member to securely retainsaid cylinderforrning means and said gas-generating means receivedtherein in assembly with said second plug member.

10. A device as recited in claim 8, said second plug member being formedwith an axial bore, together with aheader plug including means foractuating said gasgenerating means from an external location, saidheader plug being received conformably in said axial bore in said secondplug member and being circumferentially welded thereto.

11. A device as recited in claim 10, said cylinderforming means beingreceived in said axial bore in said second plug member, said header plugoverlying and positioning said cylinder-forming means with respect tosaid second plug member.

12. A device as recited in claim 11, together with a ferrule received insaid cylinder-forming means between said header plug and said piston tolocate said piston in a retracted position spaced apart from said headerplug.

13. A device as recited in claim 12, said gasgenerating means beingreceived in said ferrule.

14. A device as recited in claim 8, said piston being formed with afirst circumferential flange portion conformably and slidably receivedin said cylinder-forming means, and with a second circumferential flangeportion spaced apart along said piston from said first flange portion,said second flange portion being circumferentially spaced apart fromsaid cylinder-forming means;

and sealing ring means received about said piston between said flangeportions and sealingly engaging said cylinder-forming means.

15. A device as recited in claim 8, said storage chamber-forming meansbeing formed with a tapered orifice for filling said chamber with acharge of fluid, together with a taper pin sealingly engaged in saidorifice with a force fit.

16. A device as recited in claim 8, said spool being of a length to abutsaid shell at each of said central openings at said opposite axial endsthereof.

17. A piston-actuated fluid discharge device comprising in combination:

means forming a storage chamber for pressurized fluid, said chamberbeing provided with a fluid discharge passage;

stepped axial bore providing a circumferential seat therein, saidcylinder-forming means extendiri'g w within said bore and being formedwith an annular flange engaging said seat, together with a header plugreceived in said axial bore and overlying said flange to capture saidcylinder-forming means in said bore, said header plug beingcircumferentially welded to said chamber-forming means to securelyretain said cylinder forming means and said gasgenerating means receivedtherein in assembly with said chamber-forming means.

1. A piston-actuated fluid-discharge device comprising, in combination:means forming a storage chamber for pressurized fluid comprising anannular shell having central openings at opposite axial ends thereof, apair of plug members received conformably in said openings and weldedcircumferentially to said shell, and an annular cylindrical spoolreceived coaxially within said shell and threaded at opposite endsthereof in said plug members, said spool being formed with an openingcommunicating the interior thereof with the interior of said shell; afirst one of said plug members being formed with a fluid dischargepassage of circular cross-section; a nozzle insert overlying an inletend of said discharge passage and formed with a squared orifice portionextending into said passage; diaphragm means overlying said nozzleinsert and normally sealing said storage chamber from said dischargepassage; a second of said plug members being provided with means forpuncturing said diaphragm means including cylinder-forming meansextending axially within said spool, a piston slidably received in saidcylinder-forming means and having a tip adapted for puncturing saiddiaphragm means, and gas-generating means received in saidcylinder-forming means at an end of said piston opposite said tip fordriving said piston forwardly in said cylinder-forming means forpuncturing said diaphragm means; said piston being formed with a firstcircumferential flange portion conformably and slidably received in saidcylinderforming means, and with a second circumferential flange portionspaced apart along said piston from said first flange portion, saidsecond flange portion being circumferentially spaced apart from saidcylinder-forming means; and sealing ring means received about saidpiston between said flange portions and sealingly engaging saidcylinder-forming means.
 2. A piston-actuated fluid-discharge devicecomprising, in combination: means forming a storage chamber forpressurized fluid including an outlet plug member formed with a fluiddischarge passage of circular cross-section; a nozzle insert overlyingan inlet end of said discharge passage and formed with a generallysquared orifice portion having rounded corners, said orifice portionextending into said passage; diaphragm means overlying said nozzleinsert and normally sealing said storage chamber from said dischargepassage; means for puncturing said diaphragm means includingcylinder-forming means, a piston slidably received in saidcylinder-forming means and having a tip adapted for puncturing saiddiaphragm means, and means for driving said piston forwardly in saidcylinder-forming means for puncturing said diaphragm means.
 3. A deviceas recited in claim 2, in which said generally squared orifice portionis formed with corners rounded to a radius less than half the width ofsaid orifice portion.
 4. A device as recited in claim 2, said diaphragmbeing pre-stressed by means of crossed linear indentations extendingsubstantially along each diagonal of said squared orifice portion.
 5. Adevice as recited in claim 2, in which said chamber-forming meansincludes an annular shell having central openings at opposite axial endsthereof, a further plug member, said outlet plug member and said furtherplug member being received conformably in said openings and weldedcirCumferentially to said shell, and an annular cylindrical spoolreceived coaxially within said shell and threaded at opposite endsthereof in said plug members; said spool being formed with an openingcommunicating the interior thereof with the interior of said shell, andreceiving said piston and cylinder-forming means therein in alignmentwith said diaphragm means.
 6. A device as recited in claim 5, in whichsaid means for driving said piston comprises gas-generating meansreceived in said cylinder-forming means at an end of said pistonopposite said tip, said further plug member being formed with an axialbore receiving said cylinder-forming means, and a header plug includingmeans for actuating said gas-generating means from an external location,said header plug being received conformably in said axial bore in saidfurther plug member and being circumferentially welded thereto.
 7. Adevice as recited in claim 2, said piston being formed with a firstcircumferential flange portion conformably and slidably received in saidcylinder-forming means, and with a second circumferential flange portionspaced apart along with piston from said first flange portion towardsaid tip, said second flange portion being circumferentially spacedapart from said cylinder-forming means; together with sealing ring meansreceived about said piston between said flange portions and sealinglyengaging said cylinder-forming means.
 8. A piston-actuatedfluid-discharge device comprising, in combination: means forming astorage chamber for pressurized fluid comprising an annular shell havingcentral openings at opposite axial ends thereof, a pair of plug membersreceived conformably in said openings and welded circumferentially tosaid shell, and an annular cylindrical spool received coaxially withinsaid shell and threaded at opposite ends thereof in said plug members,said spool being formed with an opening communicating the interiorthereof with the interior of said shell; a first one of said plugmembers being formed with a fluid discharge passage; diaphragm meansnormally sealing said discharge passage, a second of said plug membersbeing provided with means for puncturing said diaphragm means includingcylinder-forming means extending axially within said spool, a pistonslidably received in said cylinder-forming means and having a tipadapted for puncturing said diaphragm means, and gas-generating meansreceived in said cylinder-forming means at an end of said pistonopposite said tip for driving said piston forwardly in saidcylinder-forming means for puncturing said diaphragm means.
 9. A deviceas recited in claim 8, said second plug member being formed with astepped axial bore providing a circumferential seat therein, saidcylinder-forming means extending within said bore and being formed withan annular flange abutting said seat, together with a header plugreceived in said axial bore and overlying said flange to capture saidcylinder-forming means in said second plug member, said header plugbeing circumferentially welded to said second plug member to securelyretain said cylinder-forming means and said gas-generating meansreceived therein in assembly with said second plug member.
 10. A deviceas recited in claim 8, said second plug member being formed with anaxial bore, together with a header plug including means for actuatingsaid gas-generating means from an external location, said header plugbeing received conformably in said axial bore in said second plug memberand being circumferentially welded thereto.
 11. A device as recited inclaim 10, said cylinder-forming means being received in said axial borein said second plug member, said header plug overlying and positioningsaid cylinder-forming means with respect to said second plug member. 12.A device as recited in claim 11, together with a ferrule received insaid cylinder-forming means between said header plug and said piston tolocate said piston in a retracted position spaced apart from said Headerplug.
 13. A device as recited in claim 12, said gas-generating meansbeing received in said ferrule.
 14. A device as recited in claim 8, saidpiston being formed with a first circumferential flange portionconformably and slidably received in said cylinder-forming means, andwith a second circumferential flange portion spaced apart along saidpiston from said first flange portion, said second flange portion beingcircumferentially spaced apart from said cylinder-forming means; andsealing ring means received about said piston between said flangeportions and sealingly engaging said cylinder-forming means.
 15. Adevice a recited in claim 8, said storage chamberforming means beingformed with a tapered orifice for filling said chamber with a charge offluid, together with a taper pin sealingly engaged in said orifice witha force fit.
 16. A device as recited in claim 8, said spool being of alength to abut said shell at each of said central openings at saidopposite axial ends thereof.
 17. A piston-actuated fluid dischargedevice comprising in combination: means forming a storage chamber forpressurized fluid, said chamber being provided with a fluid dischargepassage; diaphragm means normally sealing said discharge passage; meansfor puncturing said diaphragm means including cylinder-forming means, apiston slidably received in said cylinder-forming means and having a tipadapted for puncturing said diaphragm means, and gas-generating meansreceived in said cylinder-forming means at an end of said pistonopposite said tip for driving said piston forwardly in saidcylinder-forming means for puncturing said diaphragm means; saidchamber-forming means being formed with a stepped axial bore providing acircumferential seat therein, said cylinder-forming means extendingwithin said bore and being formed with an annular flange engaging saidseat, together with a header plug received in said axial bore andoverlying said flange to capture said cylinder-forming means in saidbore, said header plug being circumferentially welded to saidchamber-forming means to securely retain said cylinder forming means andsaid gas-generating means received therein in assembly with saidchamber-forming means.